LEONARDTOWN -- The mother of a slain Eastern Shore teen-ager says the death sentence handed to killer John F. Thanos "is the best justice I have seen since my boy was murdered."

"We can only hope" for the execution, said Lois Dennis, 36, of Hebron, after a St. Mary's County judge sentenced Thanos to die in the gas chamber. "But unless John Thanos decides himself to ask for it, I don't think I'll live to see it," she said, alluding to an appeals process that could become lengthy.

The decision will be automatically reviewed by the Maryland Court of Appeals, the state's highest court.

Ten other Maryland inmates face the death penalty, state corrections officials said.

The judge said he considered Thanos' troubled childhood, mental illness and an "inappropriate incarceration" at age 15 in an adult prison.

But the judge said those mitigating circumstances were outweighed by the brutal nature of the robbery and killing of Mr. Taylor. "Therefore, the court determines the sentence . . . to be death," the judge said.

"Is that death by gas?" Thanos asked, with no display of emotion.

"Death by lethal gas," Judge Kaminetz replied.

Thanos was convicted last week at a one-day non-jury trial before Judge Kaminetz.

Earlier yesterday, Thanos had told the court that given the choice between life in prison and the death sentence, he would choose life. "I think I'll take the life without parole, with the possibility for escape," Thanos said.

The convicted killer also criticized the psychiatric profession, commented on the appearance of several women in the courtroom and urged the judge to make a prompt decision.

James McCarthy, one of three public defenders representing Thanos, said Thanos' comments were an "illustration" of the findings of two defense experts who diagnosed Thanos with a mental illness.

That illness, borderline personality disorder, caused Thanos during his robbery of Mr. Taylor to lose control and impulsively shoot the young man, Mr. McCarthy argued.

B. Randall Coates, the state's attorney for Worcester County, argued that even if Thanos suffers from the mental illness, it was not the cause of the murder.

"Gregory Taylor was executed," Mr. Coates said, "because he had a car the defendant wanted."

Testimony, including a videotaped confession Thanos gave to police, revealed Mr. Taylor picked up Thanos that Friday afternoon on U.S. 50 near Salisbury. Thanos ordered him to drive to a secluded dirt logging road north of Salisbury and shot him three times in the head at point-blank range.

Thanos also could receive the death penalty when he is sentenced June 1 for the murders of two Middle River teen-agers.